Pine script Plot to float type casting

//Volume Weighted Moving Avarage
vwma_ohlc= ta.vwma(ohlc4,7)
vwma_midline =  plot(vwma_ohlc, title = "VWMA Mid Line", color = color.silver, linewidth = 2)
vwma_topline = plot(vwma_ohlc, title = "VWMA Top Line",color= color.green,offset=-5,linewidth = 1)
vwma_bottomline = plot(vwma_ohlc, title = "VWMA Bottom Line", color = color.red, offset=5,linewidth = 1)

if (ta.crossover(vwma_topline, vwma_midline) and ta.crossover(vwma_midline, vwma_bottomline))

I have this code and need a float type for 'vwma_topline' and 'vwma_bottomline' instead of plot type and still need to be able to plot these lines.

basically 'vwma_topline' and 'vwma_bottomline' are the same as 'vwma_midline' but has an offset of -5 and 5 bars respectively. I need a way to calculate a float value for these. can somebody help

vwma_ohlc= ta.vwma(ohlc4,7)
plot(vwma_ohlc, title = "VWMA Mid Line", color = color.silver, linewidth = 2)
vwma_topline = plot(vwma_ohlc, title = "VWMA Top Line",color= color.green,offset=-5,linewidth = 1)
vwma_bottomline = plot(vwma_ohlc, title = "VWMA Bottom Line", color = color.red, offset=5,linewidth = 1)

vwma_topline_val = ta.valuewhen(bar_index, vwma_topline, 0)
vwma_bottomline_val = ta.valuewhen(bar_index, vwma_bottomline, 0)

if(vwma_topline_val > vwma_ohlc and vwma_bottomline_val < vwma_ohlc)
    [0]

I have already tried this to get value but it gives me the same errors on lines 6 and 7 and basically tells me that I have entered plot type instead of series float for 'vwma_topline' and 'vwma_bottomline'.

Hope this helps (please see the comments in the script).

//@version=5
indicator("My script", overlay = true)



//Volume Weighted Moving Avarage
vwma_ohlc= ta.vwma(ohlc4,7)
vwma_midline =  plot(vwma_ohlc, title = "VWMA Mid Line", color = color.silver, linewidth = 3)
vwma_topline = plot(vwma_ohlc, title = "VWMA Top Line",color= color.green,offset=-5,linewidth = 1)
// vwma_bottomline = plot(vwma_ohlc, title = "VWMA Bottom Line", color = color.red, offset=5,linewidth = 1)

vwma_ohlc_bot = vwma_ohlc[5]
vwma_bottomline2 = plot(vwma_ohlc, title = "VWMA Bottom Line", color = color.red, offset=5,linewidth = 1)
cross_bottom = ta.cross(vwma_ohlc, vwma_ohlc_bot)
plotshape(cross_bottom, "Cross Bottom", style = shape.xcross, color = color.red )


// the value of vwma_topline for the current bar will only be available five bars ahead, so we cannot have the value now
// but the cross of mid and top lines is always 5 bars behind the cross of the bottom and mid lines
plotshape(cross_bottom, "Cross Top", style = shape.xcross, color = color.green, offset = -5 )


// if (ta.crossover(vwma_topline, vwma_midline) and ta.crossover(vwma_midline, vwma_bottomline))
//plot(close)